Update README.md

Author: yamankatby

README.md

@@ -11,3 +11,7 @@ Optionally, this extension can be configured to delete the user's document when
 [👀 Documentation](https://github.com/rowyio/firebase-extensions/tree/main/firestore-user-document)
 
 [![install-extension](https://user-images.githubusercontent.com/35961879/201528504-4e99bfc7-8691-4151-b63d-0511097d7c18.png)](https://console.firebase.google.com/project/_/extensions/install?ref=rowy/firestore-user-document)
+
+## 🙏 Acknowledgements
+
+[Sandrina](https://sandrina.framer.website) for the awesome extension icon.